Automatic transmission assemblies sometimes include a piston housing member which houses a piston and its associated clutch plates. The clutch plates are engaged with internal splines of the piston housing member, and the piston housing member has external splines which are splined to a transmission case. The piston housing member may be axially secured with respect to the transmission case by one or more snap rings to axially ground forces of the piston.
With the clutch plates splined into the piston housing member, the piston housing member becomes a large component which adds mass and cost to the transmission assembly.